This recipe will describe how the External links module can be used to style URLs linking to external sites and links which use the mailto: protocol to reference e-mail addresses.
The External links module can be downloaded from http://drupal.org/project/extlink and is assumed to have been enabled.
The External links module works out of the box as it functions based on JavaScript. To see the module in action, create or edit a node with the following modifications:
Add a link to an internal URL: for example,
<a href="/about">About us</a>
Add a link to an external URL:
<a href="http://drupal.org">Drupal</a>
Add an e-mail link using the mailto protocol:
<a href="mailto:[email protected]">[email protected]</a>
Once the node is saved, we should be able to see the external and mailto: link styled something as shown in the following screenshot: